The optic tectum grows continuously by the addition of cells produced in a proliferative zone located at the margin of the structure (Nguyen et al., 1999). This proliferative zone therefore exhibits, in dorsal view, a quite characteristic annular shape. This peculiar mode of growth allows to determine easily and quickly whether a gene is expressed in proliferating cells (marginal zone) of in differentiared cells (central zone). We performed several in situ screens (Nguyen et al., 2001, Mechanisms of Development, 107, 55-67 ; Deyts et al., 2005, Developmental Dynamics, 234, 698-708) and isolated a sizeable number of previously uncharacterized genes, which could represent novel regulators of cell proliferation. In addition, we detected a third class of genes, expressed in an open ring of cells located between the marginal (proliferative) zone and the central (differentiation) zone (see Fig. 1). These genes correspond to negative regulators of cell proliferation (cell cycle arrest genes). More recently, we identified a zone of relatively slow cycling progenitors in the peripheral midbrain layer (PML), bordering the tectum, which have molecular features similar to drosophila neuroblasts and mammalian stem cells. This population of stem cells should become a pioneering cellular model for the study of neural stem cell.

Project 1:

Function of tumor suppressor genes in the development of the medaka optic tectum. Person in charge: Franck Bourrat